[PATCH] D41615: [DebugInfo] Don't crash when given invalid DWARFv5 line table prologue.

[Jonas Devlieghere via Phabricator via llvm-commits]

JDevlieghere created this revision.
JDevlieghere added reviewers: probinson, aprantl.
JDevlieghere added a project: debug-info.

This patch replaces an assertion with an explicit check for the validity
of the FORM parameters. The assertion was triggered when the DWARFv5
line table contained a zero address size.

This fixes OSS-Fuzz Issue 4644
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=4644


Repository:
  rL LLVM

https://reviews.llvm.org/D41615

Files:
  include/llvm/DebugInfo/DWARF/DWARFFormValue.h
  lib/DebugInfo/DWARF/DWARFDebugLine.cpp
  lib/DebugInfo/DWARF/DWARFFormValue.cpp
  test/DebugInfo/Inputs/invalid.linetable
  test/DebugInfo/dwarfdump-invalid-line-table.test


Index: test/DebugInfo/dwarfdump-invalid-line-table.test
===================================================================
--- /dev/null
+++ test/DebugInfo/dwarfdump-invalid-line-table.test
@@ -0,0 +1,5 @@
+Verify that dwarfdump doesn't crash on invalid line table prologue.
+OSS-Fuzz Issue 4644 (https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=4644)
+
+RUN: llvm-dwarfdump --verbose %p/Inputs/invalid.linetable 2>&1 | FileCheck %s --check-prefix=INVALID-LINE-TABLE
+INVALID-LINE-TABLE: invalid directory or file table description
Index: lib/DebugInfo/DWARF/DWARFFormValue.cpp
===================================================================
--- lib/DebugInfo/DWARF/DWARFFormValue.cpp
+++ lib/DebugInfo/DWARF/DWARFFormValue.cpp
@@ -64,8 +64,10 @@
                                  const DWARFFormParams Params) {
   switch (Form) {
   case DW_FORM_addr:
-    assert(Params.Version && Params.AddrSize && "Invalid Params for form");
-    return Params.AddrSize;
+    if (Params)
+      return Params.AddrSize;
+    else
+      return None;
 
   case DW_FORM_block:          // ULEB128 length L followed by L bytes.
   case DW_FORM_block1:         // 1 byte length L followed by L bytes.
@@ -86,8 +88,10 @@
     return None;
 
   case DW_FORM_ref_addr:
-    assert(Params.Version && Params.AddrSize && "Invalid Params for form");
-    return Params.getRefAddrByteSize();
+    if (Params)
+      return Params.getRefAddrByteSize();
+    else
+      return None;
 
   case DW_FORM_flag:
   case DW_FORM_data1:
@@ -118,8 +122,10 @@
   case DW_FORM_line_strp:
   case DW_FORM_sec_offset:
   case DW_FORM_strp_sup:
-    assert(Params.Version && Params.AddrSize && "Invalid Params for form");
-    return Params.getDwarfOffsetByteSize();
+    if (Params)
+      return Params.getDwarfOffsetByteSize();
+    else
+      return None;
 
   case DW_FORM_data8:
   case DW_FORM_ref8:
Index: lib/DebugInfo/DWARF/DWARFDebugLine.cpp
===================================================================
--- lib/DebugInfo/DWARF/DWARFDebugLine.cpp
+++ lib/DebugInfo/DWARF/DWARFDebugLine.cpp
@@ -268,7 +268,7 @@
 
   if (getVersion() >= 5) {
     if (!parseV5DirFileTables(DebugLineData, OffsetPtr, EndPrologueOffset,
-                              getFormParams(), U, HasMD5, IncludeDirectories,
+                              FormParams, U, HasMD5, IncludeDirectories,
                               FileNames)) {
       fprintf(stderr,
               "warning: parsing line table prologue at 0x%8.8" PRIx64
Index: include/llvm/DebugInfo/DWARF/DWARFFormValue.h
===================================================================
--- include/llvm/DebugInfo/DWARF/DWARFFormValue.h
+++ include/llvm/DebugInfo/DWARF/DWARFFormValue.h
@@ -50,6 +50,8 @@
     }
     llvm_unreachable("Invalid Format value");
   }
+
+  explicit operator bool() const { return Version && AddrSize; }
 };
 
 class DWARFFormValue {


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